I know the first gear pinion will thread rite on. I tried one of there 15 tooth pinions. It is not hard anodized so it will not last as long. As far as the rest of kyosho's 1/8th drive-train; keep in mind Lamberto Collari replaced his entire Kyosho drive train with Mugen's at the 09 Worlds...
Try nitrohouse for the Mugen stuff.